Generalized Social Marginal Welfare Weights Imply Inconsistent Comparisons of Tax Policies

This paper concerns Saez and Stantcheva's (2016) generalized social marginal welfare weights (GSMWW), which aggregate losses and gains due to tax policies, while incorporating non-utilitarian ethical considerations. The approach evaluates local tax changes without a global social objective. I show that local tax policy comparisons implicitly entail global comparisons. Moreover, whenever welfare weights do not have a utilitarian structure, these implied global comparisons are inconsistent. I argue that broader ethical values cannot in general be represented simply by modifying the weights placed on benefits to different people, and a more thoroughgoing modification of the utilitarian approach is required.